Wireless communications systems employ a number of geographically distributed, cellular communication sites or base stations. Each base station supports the transmission and reception of communication signals to and from stationary or fixed, wireless communication devices or units. Each base station handles communications over a particular region commonly referred to as a cell/sector. The overall coverage area for a wireless communications system is defined by the union of cells for the deployed base stations. Here, the coverage areas for adjacent or nearby cell sites may overlap one another to ensure, where possible, contiguous communications coverage within the outer boundaries of the system.
When active, a wireless unit receives signals from at least one base station over a forward link or downlink and transmits signals to at least one base station over a reverse link or uplink. Several approaches have been developed for defining links or channels in a cellular communication system. These schemes include, for example, TDMA (time-division multiple access), and CDMA (code-division multiple access).
In TDMA communication systems, the radio spectrum is divided into time slots. Each time slot allows only one user to transmit and/or receive. Thusly, TDMA requires precise timing between the transmitter and receiver so that each user may transmit their information during their allocated time.
In CDMA communications systems, different wireless channels are distinguished by different channelization codes or sequences. These distinct channelization codes are used to encode different information streams, which may then be modulated at one or more different carrier frequencies for simultaneous transmission. A receiver may recover a particular stream from a received signal using the appropriate code or sequence to decode the received signal.
Referring to FIG. 1, an exemplary network 10 supportive of wireless communications is illustrated. Here, network 10 may accommodate one of a number of standard architectures, including the Universal Mobile Telecommunications System (“UMTS”) and/or Code Division Multiple Access (“CDMA”) systems, for example. Network 10 may be divided into a radio access network (“RAN”) 12 and a core network 14. RAN 12 includes equipment used to support wireless interfaces 16a and 16b between exemplary wireless units, 18a and 18b, and network 10. RAN 12 also comprises a plurality of Node Bs or base stations 20a through 20c, as well as a number of radio network controllers (“RNCs”) or base station controllers, 22a and 22b. The signaling exchange between the Node Bs and RNCs is commonly referred to as the Iub interface, while the interface between RNCs themselves is commonly referred to as the Iur interface. The transport mechanism of both the Iub and Iur interfaces is generally based on asynchronous transfer mode (“ATM”).
Core network 14 includes network elements that support circuit based communications, as well as packet-based communications. In establishing a circuit channel to handle circuit-based communications between the wireless unit 18b and a public switched telephone network (“PSTN”) 24 or another wireless unit, for example, base station 20b may receive (in the uplink) and transmits (in the downlink) coded information (e.g., circuit voice or circuit switched data) over the wireless interface or link 16b. RNCs 22a and 22b may each perform a number of functions, including frame selection, encryption, and handling of access network mobility, for example. In the above scenario, RNC 22b may forward the circuit voice and circuit switched data over a network, such as an asynchronous transfer mode (“ATM”)/Internet Protocol (“IP”) network 28 to a mobile switching center (“MSC”) 30. MSC 30 is responsible for call processing and macromobility on the MSC level. MSC 30 establishes the connectivity between wireless unit 18b, for example, and PSTN 24.
In establishing a packet channel to handle packet-based communications between exemplary wireless unit 18a and a packet data network (“PDN”) 34, such as the Internet, base station 20a receives (in the uplink) and transmits (in the downlink), coded information over the wireless interface or link 16a. In the uplink direction, RNC 22a reassembles the packets as sent by exemplary wireless unit 18a and forwards them to a serving GPRS (e.g., General Packet Radio Service) support node (“SGSN”) 40. In the downlink direction, RNC 22a receives the packets and segments them into the right size packet to be transferred to the base station, which may perform its processing and the data across the wireless link 16a. SGSN 40 provides packet data session processing and macromobility support for network 10. SGSN 40 establishes connectivity between wireless unit 18a and PDN 34.
Additionally, core network 14 may also include a gateway GPRS support node (“GGSN”) 42. GGSN 42 may act as the gateway to external PDNs, for example. Upon requests from SGSN 40, GGSN provides a gateway for packet data protocol (“PDP”) session establishment.
For voice applications, conventional cellular communication systems employ dedicated links between a wireless unit and a base station. Voice communications are delay-intolerant by nature. Consequently, wireless units in wireless cellular communication systems transmit and receive signals over one or more dedicated links. Each active wireless unit generally requires the assignment of a dedicated link on the downlink, as well as a dedicated link on the uplink.
With the explosion of the Internet and the increasing demand for data, resource management has become a growing issue in cellular communication systems. Next generation wireless communication systems, such as those employing High Speed Downlink Packet Access (“HSDPA”) and High Speed Uplink Packet Access (“HSUPA”), are expected to provide premium data services in support of Internet access and multimedia communication. Unlike voice, however, data communications may be potentially bursty yet relatively delay tolerant. The system for data communications, as such, may not be efficient with dedicated links on the downlink or the uplink. A more efficient data communication system may be enabled if the system employs one or more channels to be shared by a number of wireless units. By this arrangement, each of the wireless units on the downlink shares available resources, where the downlink transmission is scheduled to the user(s) through a resource management process. Resources to be managed in the downlink include, for example, the allocated transmit power by the Node B, the channelization codes, and/or the interference created by each user to other users in the same sector or cell, as well as in other sectors or cells.
The general management of resources at a Node B offering HSDPA/HSUPA services may be performed by a radio network controller, such as RNC 22a and/or RNC 22b in FIG. 1. For example, each RNC may determine and control various characteristics in the transfer of data on the downlink and/or uplink for each Node B supporting HSDPA/HSUPA services. These characteristics on the downlink and/or uplink may include, for example, the allocation of transmit power and/or the transmission speed of the data packets.
Various problems have been identified in the further development of HSDPA/HSUPA services. These problems include, for example, inefficiency and performance issues in the transfer of data, as well as design implementation costs of base stations supporting HSDPA/HSUPA services. Consequently, a demand exists for a method for increasing the efficiency and performance of a network supporting HSDPA/HSUPA services. Moreover, a need exists for reducing the costs of implementing a base station supporting HSDPA/HSUPA services.